Extramedullary plasmacytoma in the trachea of a dog.

A 10-year-old spayed female mixed-breed dog was examined because of acute inspiratory dyspnea. Radiography and tracheoscopy revealed a discrete, solitary mass originating from the membranous portion of the trachea at the level of the thoracic inlet. Tracheal resection and anastomosis were performed, and on histologic examination of the resected tissue, extramedullary plasmacytoma was diagnosed. Although tracheal tumors are rare in dogs, they should be considered during evaluation of dogs with signs of airway obstruction. Prognosis is excellent for dogs with extramedullary plasmacytoma in which surgical excision is complete.